Experimental Protocol for Biodiesel Production with Isolation of Alkenones as Coproducts from Commercial <em>Isochrysis</em> Algal Biomass

The need to replace petroleum fuels with alternatives from renewable and more environmentally sustainable sources is of growing importance. ...

United States Department of Agriculture

A series of long-chain methyl esters with vicinal oxo groups (1,2-diones; 1,2-diketones) were synthesized by potassium permanganate-based oxidation of methyl esters of mono-unsaturated fatty acids. The presence of two additional carbonyl groups may facilitate the synthesis of other derivatives. The starting materials were selected in such a fashion to give the 1,2-dioxo moiety in consecutive positions from the methyl ester group. The compounds were characterized by mass spectrometry and nuclear magnetic resonance spectroscopy. In mass spectrometry, both electron and chemical ionization (methane as reagent gas) were investigated. The position of the dioxo moiety can be determined in both ionization modes, however, in electron ionization mode the corresponding fragment ions are considerably stronger. In electron ionization mode, a fragmentation mechanism depending on the position of the 1,2-dioxo moiety occurs while the spectra derived from chemical ionization mode are mainly characterized by peaks around the molecular ion with both ionization modes appearing suitable.

Synthesis and characterization of long-chain 1,2-dioxo compounds.

Cyclopropane FA occur in nature in the phosphoplipids of bacterial membranes, in oils containing cyclopropene FA, and in Litchi sinensis oil. Dihydrosterculic acid (2-octyl cyclopropaneoctanoic acid) and its methyl ester were selected for 1H and 13C NMR analysis as compounds representative of cyclopropane FA. The 500 MHz 1H NMR spectra acquired with CDCl3 as solvent show two individual peaks at -0.30 and 0.60 ppm for the methylene protons of the cyclopropane ring. Assignments were made with the aid of 2D correlations. In accordance with previous literature, the upfield signal is assigned to the cis proton and the downfield signal to the trans proton. This signal of the trans proton is resolved from the peak of the two methine protons of the cyclopropane ring, which is located at 0.68 ppm. The four protons attached to the two methylene carbons alpha to the cyclopropane ring also show a split signal. Two of these protons, one from each methylene moiety, display a distinct shift at 1.17 ppm, and the signal of the other two protons is observed at 1.40 ppm, within the broad methylene peak. The characteristic peaks in the 13C spectra are also assigned.

NMR characterization of dihydrosterculic acid and its methyl ester.

Novel multi-hydroxylated primary fatty amides produced by direct amidation of 7,10-dihydroxy-8(E)-octadecenoic acid and 7,10,12-trihydroxy-8(E)-octadecenoic acid were characterized by GC-MS and NMR. The amidation reactions were catalyzed by immobilized Pseudozyma (Candida) antarctica lipase B (Novozym 435) in organic solvent with ammonium carbamate. The mass spectra of the underivatized products exhibited characteristic primary amide peaks at m/z 59 and m/z 72 that differed in peak intensities. Other peaks present were consistent with cleavage next to the hydroxyl groups. The mass spectra of the silylated amidation products showed the correct molecular weight and the typical fragmentation pattern of silylated hydroxy compounds. The mass spectra, together with proton and 13C NMR data, suggest that the products of lipase-catalyzed direct amidation of 7,10-dihydroxy-8(E)-octadecenoic acid and 7,10,12-trihydroxy-8(E)-octadecenoic acid are, 7,10-dihydroxy-8(E)-octadecenamide and 7,10,12-trihydroxy-8(E)-octadecenamide acid, respectively. Amidation of multi-hydroxylated fatty acids had increased the melting point, but reduced the surface active property of the resulting primary amides.

Characterization of fatty amides produced by lipase-catalyzed amidation of multi-hydroxylated fatty acids.

Biodiesel is an alternative to petroleum-based conventional diesel fuel and is defined as the mono-alkyl esters of vegetable oils and animal fats. Biodiesel has been prepared from numerous vegetable oils, such as canola (rapeseed), cottonseed, palm, peanut, soybean and sunflower oils as well as a variety of less common oils. In this work, Moringa oleifera oil is evaluated for the first time as potential feedstock for biodiesel. After acid pre-treatment to reduce the acid value of the M. oleifera oil, biodiesel was obtained by a standard transesterification procedure with methanol and an alkali catalyst at 60 degrees C and alcohol/oil ratio of 6:1. M. oleifera oil has a high content of oleic acid (>70%) with saturated fatty acids comprising most of the remaining fatty acid profile. As a result, the methyl esters (biodiesel) obtained from this oil exhibit a high cetane number of approximately 67, one of the highest found for a biodiesel fuel. Other fuel properties of biodiesel derived from M. oleifera such as cloud point, kinematic viscosity and oxidative stability were also determined and are discussed in light of biodiesel standards such as ASTM D6751 and EN 14214. The 1H NMR spectrum of M. oleifera methyl esters is reported. Overall, M. oleifera oil appears to be an acceptable feedstock for biodiesel.

Moringa oleifera oil: a possible source of biodiesel.

Eighteen Pseudomonas aeruginosa strains were examined for their ability to convert oleic acid to produce 10-hydroxy-8(E)-octadecenoic acid (HOD), which was structurally confirmed by GC-MS, NMR, and FTIR. There were no substantial amounts of other new compounds found in the fermentation broths in addition to HOD and 7,10-dihydroxy-8(E)-octadecenoic acid (DOD). The results demonstrated that P. aeruginosa strains possessed varying levels of activity for producing HOD. Under the experimental conditions, strain NRRL B-14938 isolated from sheep manure was the best HOD producer exhibiting the highest HOD to DOD product ratio in the medium most suitable for purifying HOD. Using strain B-14938 as a model system for further characterization, optimum conditions for producing HOD were found to be at 26 degrees C and pH 7.0 after 60 h of reaction time using a medium containing EDTA as a chelating agent. This study has identified a high-yielding P. aeruginosa strain and provided the reaction characteristics needed to develop a scale-up production process of HOD for testing its properties and potential new uses.

Production of 10-hydroxy-8(E)-octadecenoic acid from oleic acid conversion by strains of Pseudomonas aeruginosa.

Used cooking or frying oils are of increasing interest as inexpensive feedstock for biodiesel production. In this work, used frying oils obtained from 16 local restaurants were investigated regarding their fatty acid profile vs. the fatty acid profile of the oil or fat prior to use. The fatty acid profiles were analyzed by gas chromatography and proton nuclear magnetic resonance spectroscopy. Besides the fatty acid profile, the acid value and dynamic viscosity of the samples were determined. Dynamic viscosity was determined because of non-Newtonian behavior of some samples. The results indicate that oils and fats experience various degrees of increase in saturation during cooking/frying use, with the magnitude of these changes varying from sample to sample, i.e., a high degree of randomness of composition is found in used frying oil samples. Properties of the samples that were investigated were acid value and viscosity which consistently increased with use, also in a random fashion. Multiple independent samples obtained from the same restaurants indicate that there is little consistency of used cooking oil obtained from the same source. These results are discussed with regards to the potential fuel properties of biodiesel derived from these used frying oils.

A comparison of used cooking oils: a very heterogeneous feedstock for biodiesel.

Biodiesel is a generic term for fuel that can be made from virtually any plant or animal oil via transesterification of triglycerides with an alcohol (and usually a catalyst). Biodiesel has received considerable scientific attention in recent years, as it is a renewable resource that is directly able to replace mineral diesel in many engines. Additionally, some countries have mandated a minimum biodiesel content in all diesel fuel sold on environmental grounds. When combusted, biodiesel produces exhaust emissions containing particulate matter, adsorbed chemicals and a range of gases. In many cases, absolute amounts of these pollutants are lower in biodiesel exhaust compared with mineral diesel exhaust, leading to speculation that biodiesel exhaust may be less harmful to health. Additionally, engine performance studies show that the concentrations of these pollutants vary significantly depending on the renewable oil used to make the biodiesel and the ratio of biodiesel to mineral diesel in the fuel mix. Given the strategic and legislative push towards the use of biodiesel in many countries, a concerning possibility is that certain biodiesels may produce exhaust emissions that are more harmful to health than others. This variation suggests that a comprehensive, systematic and comparative approach to assessing the potential for a range of different biodiesel exhausts to affect health is urgently required. Such an assessment could inform biodiesel production priorities, drive research and development into new exhaust treatment technologies, and ultimately minimize the health impacts of biodiesel exhaust exposure.

Gerhard Knothe

Agricultural Research Service

United States Department of Agriculture

Experimental Protocol for Biodiesel Production with Isolation of Alkenones as Coproducts from Commercial Isochrysis Algal Biomass

Gerhard Knothe

.css-o250i3{font-size:18px;font-family:Open Sans,sans-serif;line-height:21.6px;}Agricultural Research Service

United States Department of Agriculture

Experimental Protocol for Biodiesel Production with Isolation of Alkenones as Coproducts from Commercial Isochrysis Algal Biomass

Agricultural Research Service